Embedded systems are increasingly present in many electronic devices. Therefore, it is necessary to use rigorous testing techniques aimed at ensuring that these systems behave as expected. The authors' contribution is the definition of mutant operators for the context of embedded systems models. They focus on dynamic systems models, specifically on Simulink and Scicos models, which are considered standards in many industrial application domains, such as avionics and automotive control. The HAZOP study was applied to investigate and analyze all the main features of such models, in order that the resulting mutant operators could be systematically generated.